Siege Game Mode:

• “We have made several updates to the Siege game mode. Our goal is to improve the early to late game scaling, and ensure there are enough incentives to both capture the objective as well as push the payload cart successfully. We have also added additional incentives for champions in each role to play to their strengths. We will continue to evaluate Siege in coming patches.”
• Objectives and Payload carts no longer progress faster with multiple players, one player will give the maximum amount of progress.
• Objective capture rate and Payload cart speed now increases over the course of the match. (Seems to be stable capture rate throughout the match, not sure how to test cart speed but I will assume it's the same speed)
• The team that captures the Objective gains an additional 300 credits per player. (Tested, you gain 0)
• The defending team no longer gains credits when successfully defending the Payload push. (Still gain 200 credits)
• Objective capture rate and Payload cart speed is no longer altered when you are ahead or behind in points.
• The respawn time of both teams increases over the course of a match. [RETRACTED]

.

So the only changes that went through are:

• 1 player cap on point

• Capture rate not being altered if ahead/behind (although I've never noticed this before)

Each role now gains additional credits for doing their intended role:

• Front Line champions gain 100% more credits for standing near an objective.
• Support champions gain 100% more credits for healing allies.
• Flank champions gain 100% more credits for eliminations on enemies when they are behind enemy lines.
• Damage champions gain 100% more credits for dealing damage to enemy champions.

To elaborate:

• Frontline one is straightforward, they get doubled the rewards when capturing objective and pushing cart. This buffs their credit gains the most.

• Supports seem to get 40 credits for healing teammates at a fast rate. Not sure on the cooldown of this or specifics.

• Flanks get 100% more credits for solo kills on enemies when they are on their half of the map, when capturing point. I haven't tested if they get credits when we are pushing.

• Damage dealers get more credits for the "Damage Dealer" proc. 40 instead of 20 credits. Probably the least important buff.