I have been trying to use Safe Boot at start up as suggested in an attempt to solve a mail problem but I am distracted by the fact that the log in screen is completely different in Safe Mode (old adress/old phone number ) appears un like the norma

Do not install and run CleanMyMac! It is considered by most users here to be akin to malware. There is no reason to ever install or run any 3rd party "cleaning", "optimizing", "speed-up", anti-virus, VPN or security apps on your Mac.  This user tip describes what you need to know and do in order to protect your Mac: Effective defenses against malware and other threats - Apple Community.  

There are no known viruses, i.e. self propagating, for Macs.  There are, however, adware and malware which require the user to install although unwittingly most of the time thru sneaky links, etc.   

Anti Virus developers try to group all types as viruses into their ad campaigns of fear.  They do a poor job of the detecting and isolating the adware and malware.  Since there are no viruses these apps use up a lot of system resources searching for what is non-existent and adversely affect system and app performance.

There is one app, Malwarebytes, which was developed by a long time contributor to these forums and a highly respected member of the computer security community, that is designed solely to seek out adware and known malware and remove it.  The free version is more than adequate for most users.  

As far as the login screen for Safe Boot you should see this in the upper right hand corner:

Safe Boot does the following:

• Verifies your startup disk and attempts to repair directory issues, if needed

• Loads only required kernel extensions (prevents 3rd party kernel/extensions from loading)

• Prevents Startup Items and Login Items from opening automatically

• Disables user-installed fonts 

• Deletes font caches, kernel cache, and other system cache files

So reboot normally and then try another Safe Boot to see if the login window is what you expect. The screenshot above was from a Monterey safe boot, hence the color.

The best antivirus, cleaning app, and overall maintenance app for Mac OS is Mac OS itself. All you need to do with Mac OS to keep it secure and running well is to keep it up-to-date and do periodic (about 1x per week) restarts. Other than that, leave it alone. Adding third party antivirus, cleaning, security and other types of maintenance apps to Mac OS adds no additional level of security. The only thing these apps do is have the opposite affect users want. They make Mac OS slow, unstable, generate odd behavior (much like you are experiencing) and make Mac OS appear buggy. 

Please locate the developers uninstall instructions for CleanMyMac and follow to the letter. Then restart in Safe Mode per the directions in Use safe mode to isolate issues with your Mac and then restart normally. 

Have you followed the procedure in this article?

Start up your Mac in safe mode – Apple Support (UK)

CleanMyMac is the last thing you should be using. It is well known for causing more problems than much of what is actually labeled as "malware". It's good at deleting things that shouldn't be deleted.

Modern operating systems are designed to make use of as much of the available RAM as possible. That's normal. If you don't have enough physical RAM, there is nothing you can do with software to fix that.

What is your Mail problem?