6 month old has turned in to a nightmare

We adopted our rescue lurcher about 1.5 months ago now and for the most part, she has been fantastic. However in the last couple of weeks she has started new annoying behaviours and is having super bad reactions when we tell her to stop. She continually tries to chew our brick wall, for example, which is something she never used to do. I think it is attention seeking behaviour. Once I tell her “leave it” (which is a command she knows well and will do easily for treats), she sometimes stops but other times chooses to ignore. The we make an “ah ah” noise or say “no” and sometimes this works, but other times she will throw a full tantrum. She will bark, show teeth, snarl and bite. Literally her whole face changes and she looks like a little monster.

This used to happen sometimes when she was overtired, but now it seems to be more frequent and more extreme regardless of how much sleep she gets. It’s always when we try and stop her doing something she wants or when she wants attention from one of us.

I don’t think that lack of stimulation is an issue. Today I have taken her on a 45 min walk to the park, played with her 2/3 times, done some short training sessions with her, fetch and another 10 min sniff around the nearby field on the long lead. I also make sure to “wind down” from playtime by saying “all done” and giving her something to chew. And still she has barked/got bitey with me numerous times because I won’t let her eat things she shouldn’t or destroy my plants!

I have read that the best thing to do is ignore and walk out the room. I have been doing this consistently and try and not give her a huge reaction when she is behaving like this. If she does 2 or 3 tantrums in a row at me after the reverse time-outs I put her in the crate for a few minutes to calm down. It seems to work but I don’t want to constantly be putting her in there and give her a negative association with it.

I’m wondering if anyone has any advice. Is this the beginnings of adolescence and totally normal or is there something wrong? And if it is adolescence please please tell me it gets better lol