Been thinking about your dilemma for a bit. Honestly, for a church ceremony, you might want to consider the Canon RF 15-35mm f2.8L IS USM as the safer bet. I would suggest being careful with f4 glass in low light because stabilization wont stop subject motion blur during the vows. You should check the comparison tools on The Digital Picture website to see the distortion profiles... the Canon RF 14-35mm f4L IS USM relies a lot on software fixes which can soften the corners. Since you have the $2200 budget, just get the f2.8 and avoid the stress of noisy files. It is a beast of a lens tho, so be ready for the weight on your wrist. Better to have that extra light and not need it than the other way around.

^ This. Also, you gotta think about the physics of it... that extra stop on the Canon RF 15-35mm f2.8L IS USM is huge for autofocus speed in low light. f4 can sometimes hunt when it gets really dim, which is the last thing you want during the exchange of rings. The distortion on the Canon RF 14-35mm f4L IS USM is basically baked into the design. It is technically wider than 14mm and then cropped down via software to fix the heavy barrel look. It works, but it is not as clean as the more expensive 2.8 glass. If you are really worried about the tiny venue and need even more speed, maybe look at the Canon RF 24mm f1.8 IS STM. It is a decent option if you want to save weight and get a faster aperture for the dark corners of an old church. Honestly tho, just get the 15-35mm. It is the reliable choice for pros and fits right in your budget. You wont regret having that f2.8 when the sun goes down.