Lockdown - This needs to change!

You Guys are aware this is supposed to be a PvPvE mode right?

And exactly as the name suggests, it is Player vs. Player, meaning, other teams are going to be there trying to sabotage you as well, and you should do the same, it is a fundamental part of the gameplay loop.
The strategy you mention is widely known I even think between the devs too, it is a genius idea, Claim a truck before another one can do so so they can't escape with the Hot Ride and therefore the fight can be more challenging and the stakes would be higher, it's smart and also carries the risk that later on lowers your chances to be able to reach the truck and escape as there will be more people around, it's a gamble.

When it comes to the lockdown zone Damage, I've been on low health during it but I've never been to critical or even wrecked between waiting for the Gas Station Refill at all, if anything, it's overly generous with even B class cars being able to survive easily, add to the fact that you can repair yourself free of charge by swaping to a random Jackspot and then swapping your car back on the spot, try it.

The whole solo Session thing still happens pretty often if you set your crew to Private, and even if it isn't as populated, it will be very low players when Solo Party is being done so there shouldn't be that many issues to try and get stuff (I personally find it annoying, as this is the only mode I don't feel bad about getting into Car Combat in, better here than in PvP Races)

I really don't need this mode to last any longer, it already becomes too adicting for me to do more than one Lockdown and it lasting over 30 Minutes is already a huge time waster for me lmaooo

And those specific "secret" Impounds are supposed to be that... secrets, if everyone saw them in the map they would defend them to no end if the car was actually worth it, and it also takes away from the reward of exploration if there are no "secrets" to uncover...

Overall I see that a lot of your enfasis for your criticism here is to make the mode less "Stressful", which, while I understand that it is fair to just want to unwind and not feel pressured when playing games.... this mode was made to be challenging and nerveracking by taking inspiration from one of the most difficult games in the series, and many enjoy it for the reason of it being a challenge.

The only thing I would love the team to implement would be to have a better communication method for those who don't want to play with Voice Chat, the struggle is real when playing with randoms, finding something that's worth it or ask for help with the limited options of the chat Wheel and there not being useful presets for it when playing Lockdown on it's own

Aside from that, tweaks to fix issues when people's inventories get corrupted mid-game, a few fine tunings to the mid end challenges and a way to give Racer X Challenges more urgency would be my actual criticisms for the mode, it is pretty fun but it can also be hella frustrating, and that's the charm of it.