Going off the cfldb website, this is what it says:
2013-2016 capacity is listed at 33,422.
2017-present capacity is listed at 33,022.
In 2013 in our inaugural game we had 33,500 listed as the attendance. We got there again in that year’s Banjo Bowl. So I regarded that number as a full sellout.
2014 two announced sellouts, both against the Riders. Attendance recorded as 33,234, so that appeared to be the new sellout number.
2015 Banjo Bowl was the only sellout, at 35,156 due to the expanded Grey Cup seating in place. That is the IG Field record for a Bomber game (all-time stadium record is 36,634 for that year’s Grey Cup).
2016 again Banjo Bowl is only announced sellout at 33,234.
2017 despite the supposed reduction in seating capacity by 400, the Banjo Bowl sellout records an attendance of 33,134. Only sellout that year. This exact scenario and numbers are recorded in 2018 and 2019.
2021 Banjo Bowl only sellout at 33,234.
2022 back-to-back sellouts for Rider games, recorded as 33,234.
2023 4 announced sellouts (and counting, hopefully) and they are recorded as 32,344 at the Banjo Bowl and 32,343 at the next 3, despite the official capacity still being listed at 33,022 still. So I guess the official “sellout” mark is now 32,343, having changed this year (not sure what renos were done to reduce capacity). Looks like the 1987 record is safe until 2025 at least.