as a big time "they wouldn't fucking say that" enthusiast, i am glad those fics are written anyway.
i am currently reading a fic where mc is depicted starkingly ooc imo, in a way she seems the opposite of what she is in canon (imo). and i am having a good time bc of author's interpretation of the plot and real life facts integration.
depending on how many grey areas there are in your canon lore, anything other than canon might be ooc bc the characters wouldn't have an opportunity to do that. and as for being in line with canon behaviour - same person can act differently depending on outside factors, and people change, which is why there are long fanfics that start very "in character" but have little resemblance to the blorbo bingus towards the end.
sometimes a fic is worth overlooking ooc behaviour. sometimes it isn't for me as a reader - and then i close it and go on with my day, nothing bad happens, and if you had fun writing it (and other readers possibly had fun reading it), that what's matters! if you strive specifically to write them in character, you can always learn afterwards from a discussion in comments if you want to. if you don't care about ooc stuff in the first place, nobody can stop you.
tl;dr writing is cool and if you want to do it, you should
I have a lot of feelings about the rise of he would not fucking say that attitudes in fandom spaces and the paralysing effect it can have on creators. As a writer i think it’s important to just write what feels true to you and not what you think others will “approve” of. Like even as a reader i have enjoyed a variety of different characterisations that all work because the writer makes them work for a particular story. And a fic that’s written out of character to some will be in character to others. Writing fic is not your job you’re not being paid it’s your hobby please. Make them as close to canon as possible. Make them completely different. Who cares! Have fun! Have so much fun! There is an audience for every kind of fic and every kind of character interpretation i promise