There's bit of French grammar that's not well known because it's mostly found in colloquial lower class youth registers and it's not something immediately obvious if you don't pay attention, but it's been attested at least since the 90s, both in European and American varieties of French.
So, in standard prescriptive French, "ils/eux" act as a personal clitic/pronoun for both exclusively grammatically masculine groups (ie: a group of boys doing something is "ils") but also for mixed gender groups (ie: a group of boys and girls doing something is also "ils", even if there's only one boy in the group) whereas "elles" is used only for entirely grammatically feminine groups (ie: a group of all girls doing something is "elles").
Up to the 19th century, prescriptive French was more flexible in that it permitted proximity agreement, that is, agreement with the closest element in the sentence rather than the logical one: "les garçons et les filles, elles sont venues par ici" boys and girls came this way with "elles" and "venues" agreeing in gender and number with the closer element "filles" (girls), even tho the action as a whole is done by a mixed group.
This is now banned in modern prescriptive French, but feminists are trying to bring it back, and all progressive considerations asides, it's not quite clear on which basis it was "banned", since that kind of agreement seems very much alive in spontaneous spoken language, where people will regularly say things like "la majorité des gens veulent" the majority of people want, with plural agreement, even tho the "true" subject, "majorité", is singular.
But concurrently to this, in youth lower class speech, there is a phenomena where gender agreement is dropped entirely in the plural, and instead "ils/eux" is used as a true neutral pronoun, similar to English they, even for entirely feminine groups.
When this change is noticed at all (as I said, it's often innocuous despite how long it's been around), it of course horrifies conservatives, which are always horrified by linguistic change of any kind, especially when it originates in young people and the lower classes, but it also often horrifies feminists, who see in it a form of erasure of the feminine.
It is of course difficult in French to disentangle the symbolic of gender from its morphology, because the morphologically unmarked forms are effectively identical to masculine singular forms: "il a plu" it rained is in French like in English an impersonal verb, it has no real subject and the pronoun il/it is really just a dummy pronoun acting as a syntactically required filler. But in French this neuter "il" it is still identical in form to the masculine singular "il" he, and the participle "plu" rained while not agreeing with anything and thus not taking any morphology, is effectively identical looking to the situation where it would have masculine singular agreement.
I predict that this will be a source of socio-linguistic friction in the coming centuries as French grammatical gender continues to disappear and this process manifests largely by the unmarked forms (and thus symbolically the masculine forms) taking over.
Because gender has been gradually disappearing in French, pretty much since as long as there's been something that can be identified as a French language.
In common with most other Romance language, Old French in its earliest stage has already lost the neuter gender of Latin and collapsed Late Latin "elloru" their/to them (masculine and neuter plural) and "ellaru" their/to them (feminine plural) into a single "lor". But French goes much further than this.
Very early old French distinguished "los" (the or them, masculine plural) from "las" (the or them, feminine) plural, but this very quickly collapses to a single "les" with no gender distinction. Old French distinguished "lui" (to him) from "lié" (to her) but by Middle French this has collapsed to just "lui" — Old French had already collapsed the unstressed form of that pronoun to "li" for both masculine and feminine, but this form doesn't survive in the modern language.
Whereas Old French shortened "ma", "ta", "sa'" (my, your, his/her with feminine possessee) to m', t', s' if the next word started with a vowel, Modern French has substituted "mon", "ton", "son" (normally the forms for a masculine possessee) in that situation.
The loss of final -e's in pronunciation that occurred in the early modern era means that most past participles and many adjectives are now effectively undeclinable for gender, even if the prescriptive written norm insists otherwise — but by effect of contamination, this also affects participles that still theoretically have audible gender agreement, and increasingly in speech people will "forget" to mark words like "fait" done, "dit" said, "pris" taken or "détruit" destroyed for feminine even when prescriptively it would be required.
I don't know where that leaves the attempts by French feminists to feminize French by allowing for mixed endings like "les voyageur·euse·s sont arrivé·e·s". I understand where they're coming from but a lot of this feels like it only really works within the confines of French orthography, which is comically disconnected from pronunciation, and thus the whole edifice (asides from the fact that it's nowhere close from being accepted by either the establishment or the public at large) is just one major spelling reform away from being made completely irrelevant.