Limit top bed temp to BED_MAXTEMP - 10

The chances of a 10° overshoot is pretty minimal.

Marlin/src/gcode/bedlevel/G26.cpp

@@ -571,8 +571,8 @@ void GcodeSuite::G26() {
 
   if (parser.seenval('B')) {
     g26_bed_temp = parser.value_celsius();
-    if (g26_bed_temp && !WITHIN(g26_bed_temp, 40, (BED_MAXTEMP - 15))) {
+    if (g26_bed_temp && !WITHIN(g26_bed_temp, 40, (BED_MAXTEMP - 10))) {
-      SERIAL_ECHOLNPAIR("?Specified bed temperature not plausible (40-", int(BED_MAXTEMP - 15), "C).");
+      SERIAL_ECHOLNPAIR("?Specified bed temperature not plausible (40-", int(BED_MAXTEMP - 10), "C).");
       return;
     }
   }

Marlin/src/gcode/lcd/M145.cpp

@@ -52,7 +52,7 @@ void GcodeSuite::M145() {
     #if TEMP_SENSOR_BED != 0
       if (parser.seenval('B')) {
         v = parser.value_int();
-        ui.preheat_bed_temp[material] = constrain(v, BED_MINTEMP, BED_MAXTEMP - 15);
+        ui.preheat_bed_temp[material] = constrain(v, BED_MINTEMP, BED_MAXTEMP - 10);
       }
     #endif
   }

Marlin/src/lcd/extensible_ui/ui_api.cpp

@@ -609,7 +609,7 @@ namespace ExtUI {
     const int16_t e = heater - H0;
     #if HAS_HEATED_BED
       if (heater == BED)
-        thermalManager.setTargetBed(clamp(value, 0, BED_MAXTEMP - 15));
+        thermalManager.setTargetBed(clamp(value, 0, BED_MAXTEMP - 10));
       else
     #endif
         thermalManager.setTargetHotend(clamp(value, 0, heater_maxtemp[e] - 15), e);

Marlin/src/lcd/menu/menu_configuration.cpp

@@ -238,7 +238,7 @@ static void lcd_factory_settings() {
       MENU_ITEM_EDIT(int3, MSG_NOZZLE, &ui.preheat_hotend_temp[material], MINTEMP_ALL, MAXTEMP_ALL - 15);
     #endif
     #if HAS_HEATED_BED
-      MENU_ITEM_EDIT(int3, MSG_BED, &ui.preheat_bed_temp[material], BED_MINTEMP, BED_MAXTEMP - 15);
+      MENU_ITEM_EDIT(int3, MSG_BED, &ui.preheat_bed_temp[material], BED_MINTEMP, BED_MAXTEMP - 10);
     #endif
     #if ENABLED(EEPROM_SETTINGS)
       MENU_ITEM(function, MSG_STORE_EEPROM, lcd_store_settings);

Marlin/src/lcd/menu/menu_temperature.cpp

@@ -380,7 +380,7 @@ void menu_temperature() {
   // Bed:
   //
   #if HAS_HEATED_BED
-    MENU_MULTIPLIER_ITEM_EDIT_CALLBACK(int3, MSG_BED, &thermalManager.temp_bed.target, 0, BED_MAXTEMP - 5, thermalManager.start_watching_bed);
+    MENU_MULTIPLIER_ITEM_EDIT_CALLBACK(int3, MSG_BED, &thermalManager.temp_bed.target, 0, BED_MAXTEMP - 10, thermalManager.start_watching_bed);
   #endif
 
   //

Marlin/src/lcd/menu/menu_tune.cpp

@@ -143,7 +143,7 @@ void menu_tune() {
   // Bed:
   //
   #if HAS_HEATED_BED
-    MENU_MULTIPLIER_ITEM_EDIT_CALLBACK(int3, MSG_BED, &thermalManager.temp_bed.target, 0, BED_MAXTEMP - 15, thermalManager.start_watching_bed);
+    MENU_MULTIPLIER_ITEM_EDIT_CALLBACK(int3, MSG_BED, &thermalManager.temp_bed.target, 0, BED_MAXTEMP - 10, thermalManager.start_watching_bed);
   #endif
 
   //

Marlin/src/lcd/menu/menu_ubl.cpp

@@ -131,7 +131,7 @@ void _lcd_ubl_custom_mesh() {
   MENU_BACK(MSG_UBL_BUILD_MESH_MENU);
   MENU_ITEM_EDIT(int3, MSG_UBL_HOTEND_TEMP_CUSTOM, &custom_hotend_temp, EXTRUDE_MINTEMP, (HEATER_0_MAXTEMP - 10));
   #if HAS_HEATED_BED
-    MENU_ITEM_EDIT(int3, MSG_UBL_BED_TEMP_CUSTOM, &custom_bed_temp, BED_MINTEMP, (BED_MAXTEMP - 15));
+    MENU_ITEM_EDIT(int3, MSG_UBL_BED_TEMP_CUSTOM, &custom_bed_temp, BED_MINTEMP, (BED_MAXTEMP - 10));
   #endif
   MENU_ITEM(function, MSG_UBL_BUILD_CUSTOM_MESH, _lcd_ubl_build_custom_mesh);
   END_MENU();

Marlin/src/module/temperature.h

@@ -632,7 +632,7 @@ class Temperature {
         #endif
         temp_bed.target =
           #ifdef BED_MAXTEMP
-            MIN(celsius, BED_MAXTEMP - 15)
+            MIN(celsius, BED_MAXTEMP - 10)
           #else
             celsius
           #endif