I reported this issue with my ipad a few weeks ago. I tried all the usual solutions suggested, but the problem remained. It appears to have gone away for now, but clearly not because of anything I have done!
I have never had the problem occur on my iphone, so I thought it may be something to do with the new iPadOS, since I never had the problem untiI I updated to the new iPadOS operating system. However, from the many comments posted by other users, it seems
to happen on iPhones, on iPads using IOS, and with iPads using iPadOS.
There must surely be a rational explanation for this (trust certificates or whatever!) and I cannot understand why Micosoft & Apple can’t get their collective heads together & sort this issue!