u/Horaltic

I have 5 scops and this is only happening to 2 of them. They started as light tan and pretty small circles, but have gotten bigger and darker over the last 2 weeks.

The tent is at 81F (27C) . And humidity is 35%, might spike to 45% at lights off the first night after watering but otherwise is pretty stable.

I'm thinking sunburn but I'm very new to cactus and want a second opinion. Thanks in advance for anyone who outs in their 2 cents!