Something is definitely a little funky as that error message doesn't look right at all:
Files can be no larger than 1 MB bytes.
There was a bit of a bug in 7.5.3 and prior where the php.ini was set in bytes it would cause a problem. It looks like that might be the case with yours and it looks like maybe you've put in 1 MB into the max size instead of an actual number like 1048576
