I’m only nine months in this hobby at this point so take my response with a grain of salt, but yeah… that’s what my confirmed dinos looked like. Algae can bubble ofc but when it’s that many tiny bubbles (not like small boba), and especially the stringy snot looking stuff, I’d put money on yes. A new worker at my LFS told me I had Amphidinium and Prorocentrum based on their assessment with the microscope, but I also saw it and it spun on an access which I read is Ostreo. So, idk but I added pods, decreased the light schedule to a bare minimum to support what I had in the tank and added several bacterial supplements (for multiple strains, including ones that I didn’t have before) for several days, and it slowly disappeared. Good luck!
I guessed and multiple ppl said they needed more info so none of us really helped lol. Hopefully you got that microscope and know what you’re dealing with now. Let us know what you find out and what you do to treat it.