Ripple noise from TPS75633
Take another look at datasheet page 19 (https://www.ti.com/lit/ds/symlink/tps756.pdf#page=19), I think your problem rely on stability issues because of your output capacitance.

It does say to use a minimum of 47uF AND a minimum of 200mOhm ESR.
They even give you a formula and stability chart to go along.

So let's assume you've used a common 1206 MLCC 47uF 16V like: https://product.tdk.com/en/search/capacitor/ceramic/mlcc/info?part_no=C3216X5R1C476M160AB

Click on the TDK link and scroll-down to take a look at the "ESR" chart (you can even overlay your mouse to read data points from the chart), it is shown that capacitor is under 80mOhm at 1kHz.
Now take a look at the "DC Bias Characteristic" chart. Assuming your LDO outputs a standard 3.3V, the actual capacitance is about half the initial value (~23uF).

Now do you meet the requirements stated in the datasheet? I believe the answer is no.

What can you do about it? Well the answer is still in the datasheet:
"Solid tantalum electrolytic and aluminum electrolytic capacitors are all suitable, provided they meet the requirements described in this section."

And so why a different type of capacitor than MLCC? In brief, MLCC have very low ESR values which is generally great for decoupling but certain regulator design stability rely on higher ESR output values and here MLCC won't help much.
Aluminum electrolytic and tantalum capacitors, other than having much lower voltage derating than MLCC, do have higher ESR than MLCC.

In conclusion you may want to buy few of these (or any equivalent) to replace your 47uF MLCC output capacitor:
https://www.digikey.com/product-detail/en/w-rth-elektronik/860080372001/732-8989-1-ND/5728932

Let us know the result!