Available flash memory

2

Hm… something fishy going on here…

With the 2.6.2 esp8266 arduino core (platform-espressif8266 version is 2.3.1)…

[env:esp01_1m]
platform = espressif8266@2.3.1
board = esp01_1m
framework = arduino

… and …

#include <Arduino.h>

void setup() {
  pinMode(LED_BUILTIN, OUTPUT);
  digitalWrite(LED_BUILTIN, LOW);
}

void loop() {
  digitalWrite(LED_BUILTIN, !digitalRead(LED_BUILTIN));
  delay(500);
}

… I get …

RAM:   [===       ]  32.7% (used 26812 bytes from 81920 bytes)
Flash: [===       ]  33.6% (used 255752 bytes from 761840 bytes)

which looks to be correct, as the .ld script used by default for that board type defines the memory layout like this…
image

Can you double check your board is specified as esp01_1m in your platformio.ini and that you aren’t using a different linker-script via a build flag? (i.e. using one of the other memory layouts provided)