From tpwd:

The spawning requirements of striped bass are very exacting, a major factor limiting the establishment of self-sustaining populations. Spawning is successful only where they have access to a large river with sufficient current (at least 1 foot/sec) to maintain the greenish semi-buoyant eggs in suspension until they hatch. Otherwise, eggs will settle to the bottom where they will become silted over and die. Because hatching times are 36 to 75 hours, a considerable stretch of flowing water (~50 miles) is required, and only a few reservoirs contain self-sustaining populations, including Santee-Cooper, Lake Mead, and Lake Texoma. However, striped bass are readily propagated in hatcheries and periodic stockings can maintain populations in reservoirs not having tributaries suitable for spawning.

Kind of interesting read overall.

https://tpwd.texas.gov/fishboat/fish/didyouknow/coastal/gulfstripedbass.phtml

So we have basically 4-5 different size/age classes that are swimming around since the last recorded stocking. I lean towards there has been a natural spawn due to the right rains at the right time. They may be staggered sizes due to coming from the different upper brazos lakes and the fact that they are miracles that happened when they happened.

PK stripers are going to come back. I caught a dozen or so 8-10 inch stripers last week crappie fishing. The lake is also overloaded with 10-12 inch sandbass. I did boat one keeper striper. This fish was about 18 inches and was in the best shape I've ever seen a PK fish in. Lake is totally chock full of shad due to the BRA keeping the floodgates open so long.

this was a common scene. Huge schools of 2019 stocked stripers. These were 8-11" long. They had mats of gizzard shad pushed to the top.