New download fixed the issue ... thank you Ciaran!

Hello

Thank you for reporting this issue.

I have just created an update for this template which should resolve this issue for you. For details on updating your template may I suggest the following article.. https://joomla51.com/tutorials/joomla-basics/updating-your-joomla-template

If the issue persists after updating, may I suggest sending temporary administration access to your Joomla installation to info@joomla51.com and we will examine this issue further. For our reference please paste a link to this post in your email.

Ciaran

OK! This information was missing. So you have downloaded a new version of the template and the error comes after the installation. I thought it was an existing website.
here is the source code. Unfortunately I can't see what's missing.
That's where ciaran has to go...

No modules are published so not a module issue. Have two other J4 templates loaded and they don't show the white space & ?> when set as default.

Has to be with template which was just released.

Link: https://oceanwebclient8.com/

There you may have in the module position:
"Module Header-1" posted something and put in dirty code and that's the rest of it. A link to the page may be necessary for better analysis.
Of course, you could have accidentally copied something in somewhere else that produces these two characters... Partially deleting something can also have produced this...

Sorry meant upper left!