Generally when I see a high % of traffic coming from a location to an odd place, I suspect a bot. in this case, I will do a Data Warehouse export looking at IP Address, City, Browser, (you could also add device, since that is part of what you are seeing), PVs (and generally pull a full month of data - and I may do this a few times)
(I know that city is IP based, but if it's a bot it will likely come from the same 2-10 IP addresses)
I will sort highest to lowest to ensure that if the data truncates when I pull into Excel I don't loose the important stuff.
I then check for high levels of PVs from the same IP address, and if the browser data looks to be old... Generally bots tend to come from the same IP address usually record as older browsers (not always, but generally). I flag these to the management team and often we will create a custom bot rule to exclude the traffic but we can still monitor it through our bot reports.
If the traffic is split across different IPs, it's either legit traffic of the bot is more sophisticated. However, if real traffic, you could look into search engine referrals (and if you have contact with your SEO people, see if they see any upticks in Google Search Console or Bing Webmaster Tools that could explain why traffic has increased in those areas). You could also check if maybe Social Media referrals are having an impact? Being iOS that seems like it could be related to social media.. or maybe your content is now more prominent on Google News and Apple News?
Or maybe your French site has a better Core Web Vital rating and Google is promoting it more?
Or maybe there's some incorrect IP redirect happening on your code site (maybe someone added a IP based redirect to the site to try and funnel people to the correct language site, but instead it's sending people to the wrong site?)
There are a lot of things to check, and without knowing your site or the complexities around it, I can only offer these suggestions and wish you the best of luck in your investigation (we've all been there, and it's not a fun job... )