It doesn’t help for this job but,
I’m afraid the somewhat quirky nature of search on here has done you wrong. Frequently the answer to your question has nothing to do with the title so you’ve got to dig in.
There are hundreds of posts about where to find materials, including within the thread @evansd2 linked.
Within:
https://community.glowforge.com/search?q=plywood%20%20source%20order%3Alatest
I tend to find recommendations most often for Ocooch, GS2 Awards, Craft Closet, JPPlus, and Smokey Hill - but if none of those gets you what you need there are so many more!
Your comment about the cleaning not lasting makes me wonder if your exhaust has gotten clogged so the removed dust is being recirculated into the machine on the next job…