Data written to EEPROM gets randomly wiped out (rewritten as 0xff) after reset, wake from sleep, or power off/on

### Basic Infos

- [x] This issue complies with the [issue POLICY doc](https://github.com/esp8266/Arduino/blob/master/POLICY.md).
- [x] I have read the documentation at [readthedocs](https://arduino-esp8266.readthedocs.io/en/latest) and the issue is not addressed there.
- [x] I have tested that the issue is present in current master branch (aka latest git).
- [x] I have searched the issue tracker for a similar issue.
- [x] If there is a stack dump, I have decoded it.
- [x] I have filled out all fields below.

#### Platform

- Hardware: ESP8266
- Core Version: 3.1.2
- Development Env: [Arduino IDE|]
- Operating System: [Manjaro Linux]

### Settings in IDE

- Module: Sparkfun ESP8266 Thing Dev
- Flash Mode: [qio|dio|other] I don't know
- Flash Size: 512 kB
- lwip Variant: v2 Lower Memory
- Reset Method: I don't know
- Flash Frequency: [40Mhz] I don't know
- CPU Frequency: [80Mhz|160MHz] I don't know
- Upload Using: [SERIAL]
- Upload Speed: [115200] (serial upload only)

### Problem Description

My code writes to the (fake?) EEPROM with `EEPROM.write()` and `EEPROM.commit()` and reads with `EEPROM.read()` the data that has been written in previous "sessions".

Sometimes, utterly randomly, after waking up from sleep, when my sketch reads a byte from a given position, instead of the value that it had previously written, it **finds a `0xff`**.

My code had been running for **literally years without issues on a dozen identical boards**.

Recently I re-compiled and **re-uploaded with the last version of the Arduino core** on a new unit of the same identical board. I made **no changes to the relevant part of the code**, but the version compiled with the latest core has this issue.

Note that I'm observing the issue on a brand new chip, so this is **_not_** the Flash memory getting damaged by too many write cycles. Also, the old boards that are still running the code that was compiled with the old core, are still having no issue (they haven't got anywhere near 10k write cycles).

### [MCVE](https://stackoverflow.com/help/mcve) Sketch

NOTE: I cannot share the original sketch. I haven't written and tested a minimal sketch. The issue is hard to reproduce at will because it occurs randomly, but it happens often. I'm writing a minimal code example just to explain the issue, but I have _not_ run and tested the code below; consider it as explanatory pseudo-code, it may very well contain mistakes.

```cpp

#include

void setup() {
EEPROM.begin(512);
char x = EEPROM.read(0);
if (x != 'X') Serial.printf("!!! Unexpected value found in EEPROM: %d\n", x);
else Serial.println("Found expected value in EEPROM");
EEPROM.write(0, 'X');
EEPROM.commit();
}

void loop() {

}

```

### Debug Messages

```
Debug messages go here
```