This is why some users choose to disable read receipts, so at the very least it keeps it ambiguous. However, according to a report from Macworld, there is a weird bug with Apple’s Messages app that apparently still shows read receipts for iMessage even after the user has disabled the feature.
This is apparently a problem that dates back to earlier iOS and iPadOS builds, but it is still present in iOS 15 and there doesn’t seem to be a fix in sight. This means that even if you have disabled read receipts, there is a chance that the sender could still see if their messages have been read or not.
Right now since there is no permanent fix, some users have had luck restarting their iPhones in which the problem seems to fix itself, or at least temporarily. However, since it’s hard to say when the bug may or may not kick in, it’s definitely not the best solution unless you want to restart your iPhone or iPad several times a day.