Slight nitpick but they have only completed 2 legs, they were in the middle of filming the third when production was suspended.
Are you sure about that? The initial reports at the time in February 2020, implied that, but later clarification from TPTB at WRP and CBS said three legs in two countries (England and Scotland) and they were about the leave Scotland when production was paused. Given that, in general, international travel is currently predicated on vaccination and negative COVID-19 test within a short time before arrival, it would seem that the season 33 teams were being taken care of by CBS under their contestant contract stipulations. Vaccinations for other diseases are part of the medical protocols prior to actual production, there’s no contractual reason that wouldn’t have been extended to COVID-19 once the vaccines became available in early 2021.
The question on if they actually finished two legs or three legs I think still hasn't been 100% confirmed.
Every article from media outlets in February 2020 said the production was paused after three episodes were filmed.
https://variety.com/2020/tv/news/cbs-suspends-amazing-race-production-coronavirus-fears-1203519026/"The 33rd season of the global unscripted competition series — which had not yet been announced — was only a couple of weeks into production. Three episodes had been filmed thus far, according to a source, and the contestants had visited England and Scotland prior to the suspension of the production."
The confusion comes because we were only able to ever track down two legs of spoilers, not a third. Though it's possible we may have just missed a third. But it also doesn't make much sense to have 3 whole legs in one area of the world (the United Kingdom). There hasn't been three "legs" (episodes) all in the same location in a row since TAR14 with China, so going from TAR32 where we had literally every leg take place in a different country, to TAR33 having 3 legs all in the same region would be odd, though it's possible the third leg may have been a last minute replacement leg.
Other theories are that, as H_E_L_L_O mentioned, they only completed two episodes and were in the
middle of the third when they decided to shut down the production, which at this point, is what I think I'm leaning towards believing. If this is the case, I think likely what happened was all teams departed from the Pit Stop in Scotland and went to the airport to fly to their next destination, thus the leg technically did start. I think probably once all teams got to the airport, but before any of them flew to the next country, they decided to suspend the production. So it will be interesting to see how they edit this, if they tack it onto the end of episode 2 as a big cliffhanger, or if they just leave this for episode 3.
But it's worth pointing out that from the Starting Line to the day the suspension was announced was a total of 7-days. So to only have completed two legs a week in is also odd. Maybe they decided to wait out several days to monitor the COVID-19 situation in an extended Pit Stop before finally deciding to shut the production down? Who knows?