where the heck is it pulling this url from ?

when selected all prefs immediately change to 100 and not the values associated with Boinc Bam account for instance...

doing a recon on the domain I see the following:
Registry Domain ID: D206654128-CNIC
Registrar WHOIS Server: whois.namecheap.com
Registrar URL: https://namecheap.com
Updated Date: 2022-10-21T11:12:45.0Z
Creation Date: 2020-11-01T14:13:26.0Z
Registry Expiry Date: 2023-11-01T23:59:59.0Z
Registrar: Namecheap

Hostname IP Address Type Reverse DNS Netblock Owner Country
mma.xyz 13.127.82.163 A ec2-13-127-82-163.ap-south-1.compute.amazonaws.com AMAZON-02 India
cp.mma.xyz 13.127.82.163 A ec2-13-127-82-163.ap-south-1.compute.amazonaws.com AMAZON-02 India
dns1.registrar-servers.com. 156.154.132.200 NS dns1.registrar-servers.com SECURITYSERVICES United States
dns2.registrar-servers.com. 156.154.133.200 NS dns2.namecheaphosting.com SECURITYSERVICES United States
10 alt3.aspmx.l.google.com. 142.250.27.26 MX ra-in-f26.1e100.net GOOGLE United States
10 alt4.aspmx.l.google.com. 142.250.153.27 MX ea-in-f27.1e100.net GOOGLE United States
5 alt1.aspmx.l.google.com. 209.85.202.26 MX dg-in-f26.1e100.net GOOGLE United States
5 alt2.aspmx.l.google.com. 64.233.184.27 MX wa-in-f27.1e100.net GOOGLE United States
1 aspmx.l.google.com. 142.251.163.26 MX wv-in-f26.1e100.net GOOGLE United States

So what the heck and why is web preferences pointing to this ?

The url is supposed to come from the last project where you made a change to your global computing preferences. It's stored in the file 'global_prefs.xml', together with a <mod_time> (unix timestamp) which shows when the last change was made.

But I can't find any current BOINC project with the address 'https://mma.xyz/boinc'. Perhaps you joined a short-lived BOINC experiment?

I suggest you visit the website of one of your current projects: make an alteration (or create a new set of preferences) there; update your client from that project; check that the live project is now shown in the dialog; and move on from there.

Since he is using Boincstats Bam account manager he should report this to Willy at BOINCstats forums:
BAM! Bug Report
Found a bug in BOINCstats BAM? Post it here.

I suspect that BOINCstats has a misconfigured web url for the project The Ramanujan Machine which has a similar url of https://rnma.xyz/boinc/

Agreed Dr Who, found the same url, lets see what we can see:

Another namecheap reg from IS - Iceland... through cloudflare in the US.

Writing an 'r' next an 'n' may make it look on some screens and in some fonts as if it's an 'm'. rn or m, so I think they didn't copy the URL but typed it over, wrong.