Red line under text

I was using my keyboard very normally and one time i am using whatsapp i found a redline under my arabic words, I have swiftkey installed for around 7 months with the same settings and that never happened, i have read all the posts saying it's not a swiftkey error, but still it only happens with swiftkey, I turned off the spell checker of Gboard and it's turned off while I'm using gboard only, when i use swiftkey again I get the redline. The thing is it came out of nowhere, I switched from Instagram to whatsapp to find it there. So please help.