I was watching with one eye today, but I'd say all the goals against today should be chalked up to player errors, with only the first goal possibly due to poor tactical setup. With the caveat that I didn't see the Wycombe match and I heard that Toby was shockingly bad, Doherty, Dier, and Rodon had horrible performances today.
The first goal involved a communication breakdown and horrid technique by Dier. With a back 3, the CB has to be the man in charge and on the double assist either Dier needs to tell Rodon to drop off, or Dier needs to push up along with Davies to pull Mane offside. Both Rodon and Serge are hovering near Mane and it looks like Serge tells Rodon he's passing Mane off, but Rodon is in bad position. Credit to Mane and Henderson (?) who timed the ball over the top perfectly. So, Rodon likely misplayed his man Mane, but then Dier literally doesn't make a decision as to whether to cut off the cross or track Firmino running in. Dier's been pretty solid at CB over the course of the season but his awareness is shockingly bad. Many goals against Spurs this season have come in balls behind and over the top of Dier. Nevertheless, I do wonder how much Mourinho has drilled this team with a back 3 of Davies-Dier-Rodon.
On the second goal, Spurs are now in a back 4 with Doherty-Rodon-Dier-Davies. Doherty gets embarrassed by Mane on a simple turn where Doherty overplays a tackle comically. Rodon doesn't move up to challenge Mane quickly enough (everyone was marked, so why are you backing down), but Mane only gets off an OK shot. Hugo then coughs up a baaaaad rebound (just shovel it out mon ami), and Spurs are recovering so aggressively from Doherty's goof that TAA is there to slam the rebound (not going to fault Winks, Hoj, or Davies here).
On the third goal, Rodon just fucked up. It was a backbreaking mistake, and hopefully he learns from it.
This is a strong Spurs squad but they're weak at CB. Toby is nearing the twilight, Dier is still learning the position, Rodon is inexperienced, and Sanchez isn't trusted. Toss a bad mistake by Doherty into the mix, and Liverpool punished them.