well
PHP Version 7.4.33 is what I am using on the same UBB version.
But still at 10.3.38-MariaDB-log.
Another site
PHP Version 7.4.33
MYSQL Version 10.3.37-MariaDB-log
Another site
PHP Version 7.4.33
MYSQL Version 5.7.23-23
Using UBB7.5.5 with no issues.
I have seen many sites that wait to upgrade either the server or the software and get left behind when it becomes difficult to upgrade.
Meaning the software is to old to run or the server is to new to upgrade.
My 2 cents is to keep your software and server up to date as high as possible in versions.
And not wait for UBB8 .
Besides server upgrades are always making the os bigger better faster.
