2 year old seemed to stop progressing?

Did this happen to you/your kids? My toddler turns 2 tomorrow (yay!!) and I haven’t noticed further development with his hyperlexia. We went from him not speaking at 19 months to him suddenly being able to count 1-10 and accurately add/subtract/recognize numbers by 19.5 months, to fully knowing the alphabet capital and lowercase, phonic sounds, and matching words (a is for Apple) by 21 months.

I’ve noticed him spelling out words since then, asking with seeming to recognize/read some words but for the most part I haven’t noticed any more significant change! He does his alphabet backwards along with numbers which is maybe our newest change. He has hyperlexia, his pediatrician, EI, and SLP noted it for his waitlisted autism eval for next year and he’s about at a kindergarten level for what he knows already.

Do they just go through periods of big bursts of learning then seem to take it a bit easier here and there? It’s all so new and different to me, I’m not sure what to expect and if I should be doing more to encourage him progressing further, I’ve just been following his lead on what he seems interested in (ABC/123 puzzles right now).