Took more than 5 minutes for the captcha to load

I was sniping on the web app and my screen become darkened out and I can’t press anything. Kind of like when a pop up appears but there was no pop up. I didn’t close it since I heard that people get banned from that, so I ignored it and kept watching my movie. Around 5 minutes after the captcha pop up finally came up, I solved it and I could finally begin sniping again. Does this happen for anyone else? It’s kinda annoying since it stopped me from sniping for over 5 minutes. My internet I alright but I have had some issues with it before. Could this be an add blocker issue? Any help would be appreciated!