She started her stream C4ing a hole in the roof of Matsuri's house and emptying one of her storage chests before running off while Matsuri was doing another stream.
Matsuri had been present in Pekoras prechat (she messaged during it) so it's possible she heard her talking about her plans to fuck around. so later when Matsuri logged on and saw the damage to her base and the missing things she immediately suspected Pekora and went to her base to enact revenge.
During that time Pekora had already moved on to her next target and was working on blowing a hole in Suisei's roof to rob her as well. All the while Pekora is talking to her chat about how she's going to "teach these girls Rust is not a world where you get along, it's about betrayal and fighting"
Suiesei at some point in this fucks with and gets Miko after her, Suisei returns home and in a coincidence both Pekora and Miko are trying to attack Suisei's base at the same time, Miko attacks first and is very quickly dispatched by Suisei, Pekora sneaks up on to her roof during this time and plants C4 to open the roof up. Pekora ends up blaming Miko for the C4 and explosions and says she was just passing by and stopped by to see what was happening.
Suisei keeps toying with Miko and Pekora takes this chance to slip back to her base to re-arm and come back to finish the robbery when Matsuri arrives for revenge and (details unclear I didn't watch Pekora's POV during this time) Matsuri seems to have rolled Peko and took all of her explosives away minus a single piece of C4.
At this point the 4 of them all gather "peacefully" to chat, meeting at Suisei's base and Suisei finally gets her voice coms working in game. somewhat standoff atmosphere with all 4 of them inside Suise's house, Pekora very visably obvious in the fact that she's snooping through the house to scope it out, and rummaging through storage chests, Suisei spots her doing this several times. When the group goes to leave Suisei doesn't trust that Peko hasn't stolen something from one of the boxes she was looking in, so shoots her in the head to check her body to ensure nothing was stolen. The 4 then go to pekora's, and pekora gives each of them some ammunition, they then head toward Miko's.
It turns out Miko has stolen from the others, and at this point they turn on her, kill her and trap her in her house, she bunkers down and the other 3 begin smashing things to climb in her windows and kill her some more. Pekora again slips away, planning to go home and get her rocket launcher to come back and "blow everyone up and teach them that Rust is not a world where we can all get along" (minor note at some point in these 4 person travels Fubuki also joined the group but is only a minor player, at one point at Miko's she's killed by a stray grenade from Matsuri)
Peko returns home and then realizes she's been followed by Matsuri (I believe this is the point of the stream sniping claim, I think Pekora said something in that moment along the lines of "I forgot she was watching my stream" probably referencing Matsuri being present in her pre talk. Nothing happens at this point and Matsuri ends up leaving Pekora.
Pekora begins to make her way back, all the while she's talking to her chat about how she's about to show these girls "the way of the world" and that you can't trust anyone in Rust, she also for some reason decides to leave t he party or in game group or whatever, and it's noticed and the others immediately become suspicious noticing it. Pekora arrives back at Mikos, and is instantly gunned down and Miko takes all of her belongings, Pekora returns again, and is instantly gunned down once again. She'd basically made herself suspect by dropping group so and the group of girls she wanted to teach not to trust others, didn't trust her, so they declared her "kill on sight" and she was fed a healthy dose of her own medicine.