I have just figured this out from my thai pAss being rejected…you have to contact the hotel you want to go to for the SHA Plus package you can’t book it through an app (Expedia, agoda, booking, etc)
I hope this helps people out…would be nice if the thaipass system to share this on their website
TLDR : Answer Summary
A recent post revealed that when applying for the Thai Pass, it's essential to book directly with a SHA Plus hotel rather than through booking apps like Agoda or Expedia. Many users discussed their experiences, confirming that only hotels offering the Test & Go package will be recognized. While some users managed to book through apps and successfully received their Thai Pass, others faced issues due to insufficient documentation. There's confusion about the necessity of contacting hotels for SHA Plus confirmations, with differing opinions on the reliability of booking through apps where Test & Go packages are not clearly indicated.