Powercreep is something that affects every online game, and GTA Online is no exception.
In order to entice players to try out new content, video game developers often make the new content superior to old content in one way or another. Over time, this leads to moments where some old content is widely considered to be obsolete by the playerbase (or at the very least, highly inefficient).
Likewise, GTA Online has been hit by powercreep throughout the years. Powercreep goes both ways. New stuff costs more than the content found in the original release of GTA Online, yet players also have far better ways of earning that money.
Five examples of powercreep found in GTA Online
#5 - The Cayo Perico Heist

The Cayo Perico Heist removed one of the greatest hurdles to all other heists in the game: relying on other people. Not only does the Cayo Perico Heist give a good payout, but now players aren't forced to rely on randoms or their friends to grind for money.
Generally speaking, the newer heists tend to outclass the older ones in terms of payout, making it a form of financial powercreep.
#4 - Vehicle speed

More often than not, vehicles have gotten better in GTA Online. The base game's vehicles are often slower than the newer vehicles, with no base game vehicle being at the top in any relevant vehicle class.
Predictably, this also means that newer vehicles tend to be seen more often, as there is a general powercreep in terms of their effectiveness.
#3 - Mk 2 weapons

The Mk 2 weapons are upgrades of pre-existing weapons, which makes them count as powercreep by default. These new upgrades might cost more, but the damage and customization offered by them are far and away superior when compared to the original variants.
Of course, these Mk 2 variants are also superior to some of the normal weaponry found in GTA Online. Given how easy it is to make money in GTA Online these days, there's not much of a drawback in using these weapons over the original ones.
#2 - Moneymaking methods
When GTA Online was first launched, players didn't have nearly as many opportunities as they do today. Even some of the older content would end up being removed due to how outclassed they were by modern activities and features.
For example, businesses didn't exist at the beginning of GTA Online. It's an incredibly common way for some GTA Online players to make some easy money, yet older players had to make do with inferior options back then.
#1 - Weaponized Vehicles

Some vehicles have turned the freemode metagame on its head entirely. The most notorious example was the Oppressor Mk II, which not only largely outclassed the original Oppressor, but most vehicles in general.
Sometimes, these types of vehicles are given extra effects that make them outclass other vehicles entirely. Something like the Toreador being capable of going underwater makes it the best vehicle for doing so, yet it could also dominate vehicles on land and in the air.
Even something like the Oppressor Mk II and the Toreador showcases another form of powercreep in GTA Online. The former has a limited amount of missiles, yet the latter has an infinite amount.
Note: This article reflects the writer's personal views.