Unclear errors when trying to compile on different Arduino boards


We tried three of your sketches for our Arduino boards: (ardruino) Wemos LGT Nano (328);
(ardruino) ESP8266 D1 R2.

We used three (!!!) different compilers:
Arduino IDE 1.8.19 and 2.0, as well as Microchip Studio 7.0.2542

We downloaded your sketches for both AVR 328 and ESP8266 D1 R2…
But attempts to compile to a thread of the IDEs available to us (listed above) invariably give a lot of all sorts (different!!!) errors.
Which we cannot understand.
For example, often the compiler points to symbols unknown to it, the lack of declaration of variables in the sketch, or even simply says something like: “there is a syntax violation in this line.”
But what is most amazing is that when trying to compile code for Arduino (AVR 328, nano / una), Arduino studio (old and new) say "You did not fit in the memory - 135% of the program memory was used). And Microchip Studio still throws out a bunch incomprehensible errors that do not explain anything.

But the most shocking message is that the memory space has been exceeded (135% used!!!). How is that even possible? Are we using different C++ languages?!



If this is happening with the Arduino Nano, check this post and see if that helps:

Getting uLisp to run on the Arduino Nano