I ended up with a prolonged sore throat after Omicron. Turns out it was acid reflux, possibly exacerbated by the virus. I'm rather thankful my sense of taste or smell wasn't messed with.

Sorry to hear you're having prolonged symptoms that are getting in the way. Regarding which variant you had, you can guess the odds of it by checking this chart out: https://covid.cdc.gov/covid-data-tracker/#variant-proportions
Although that's US data so it's going to be somewhat different, if it was roughly 3 weeks ago it was most likely BA.5.