I still think the Webber situation was different but accept that it can be viewed as such
I think the Red Bull favouritism thing is a weird one.
Weird in the way they seem to favour 1 driver over the other by mainly giving the favoured driver more lovin' than the out of favour driver. Thats my perception anyway.
They definitely did that with Vettel over Webber & Verstappen over Ricciardo. Not sure about the 1 season Ricciardo & Vettel had together.
In the Webber / Vettel years, RB employed team-orders that favoured both drivers at different stages. There's stories of Vettel getting things like new wings & such over Webber but nothing major. I can't recall Vettel getting preferential strategy calls outside of any pre-determined team philosophy (driver in front gets option on pit stop etc). It was more the Turkey 2010 like situations. The time Webber won a race yet when he got back into the garage it seemed no-one was overly delighted.
Similar with Ricciardo / Verstappen. It was the Baku 2017 situation. It was the public "Build a team around Verstappen" comment. It was the comment Christian Horner made to Geri in the Drive to Survive series when they were walking on their farm discussing the upcoming Monaco GP last season. Even though the team had had cost Ricciardo the win in 2016, his only comment was that he'd like to see Verstappen either win or go well, I cant remember exactly what he said. Then again I will concede that bit could've just been edited that way & I may have taken the comment out of text.
As for Senna & team orders / favouritism. Outside of the rumoured preferential Honda engine thing, the only other time I know that the got his way was Lotus in 86 where he kyboshed Derek Warwick joining the team. This wasn't out of fear of Warwick but rather a concern that Lotus didn't have the resources to support 2 #1 drivers & remain competitive, so in the end Lotus signed up Johnny Dumfries.
He copped a pasting off the British media for it at the time but in retrospect most agreed it was the right decision & seeing the speed that Lotus declined after he left, it's hard to argue.